How do heat transfer and internal energy differ? Do this by considering the number of ways that each could be formed (the number of microstates in each macrostate). In an air conditioner, 12.65 MJ of heat transfer occurs from a cold environment in 1.00 h. (a) What mass of ice melting would involve the same heat transfer? If the system as a whole is at rest, so that the bulk mechanical energy due to translational or rotational motion is zero, then the Suppose you have an ideal refrigerator that cools an environment at \(\displaystyle −20.0ºC\) and has heat transfer to another environment at \(\displaystyle 50.0ºC\). How does the kettle maintain its internal energy? (Consult Table. Solution Should the system’s entropy be high or low? These are the answers to the thermodynamics practice questions for A-Level Physics. 15. Explain your answer. Resources About Services Blog Contact Resources About Services Blog Structured or uniform? 17. How is heat being transferred? Does this imply that adiabatic processes are reversible? (a) \(\displaystyle −2.38×10^{–23}J/K\) These are the answers to the oscillations practice questions for A-Level Physics. (d) Does either outcome violate the second law of thermodynamics? (b) What if you get 75 heads and 25 tails? All the individuals who are currently preparing for any physics subject related exam or just want to improve their general knowledge related to this topic, should attempt these tests in order to complete … 49. Ideal for students preparing for semester exams, GATE, IES, PSUs, NET/SET/JRF, UPSC and other entrance exams. Explain why heat pumps do not work as well in very cold climates as they do in milder ones. What would the hot reservoir temperature be for a Carnot engine having that efficiency, if it operates with a cold reservoir temperature of \(\displaystyle 200ºC\)? It is unlikely that a process can be isothermal unless it is a very slow process. Assume that the turbines at a coal-powered power plant were upgraded, resulting in an improvement in efficiency of 3.32%. Why do refrigerators, air conditioners, and heat pumps operate most cost-effectively for cycles with a small difference between \(\displaystyle T_h\) and \(\displaystyle T_c\)? (a) \(\displaystyle 1.44×10^7J\) 20. In the English speaking part of the world thermodynamics is often seen as a subset of the ﬁeld of statistical mechanics. 41. Explain why a building made of bricks has smaller entropy than the same bricks in a disorganized pile. These are practice examination questions on liquids & gases for A-level Physics. (a) How much more electrical energy is produced due to the upgrade? 8. 15.2: The First Law of Thermodynamics and Some Simple Processes. These are practice examination questions on AC theory for A-Level Physics. 68. Steam to drive an old-fashioned steam locomotive is supplied at a constant gauge pressure of \(\displaystyle 1.75×10^6N/m^2\) (about 250 psi) to a piston with a 0.200-m radius. (c) What about in an adiabatic process (where heat transfer occurred prior to the adiabatic process)? 40. Calculate the net work output of a heat engine following path ABCDA in the figure below. (b) How many hours of operation would be equivalent to melting 900 kg of ice? (a) –56.3ºC (a) \(\displaystyle 2.47×10^{14}J\) (a) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of \(\displaystyle 50.0ºC\) and a cold reservoir temperature of \(\displaystyle −20.0ºC\)? 8. 50. This is the currently selected item. Definitions of efficiency vary depending on how energy is being converted. These are practice examination questions on synoptic for A-Level Physics. With \(\displaystyle 2.56×10^6J\) of heat transfer into this engine, a given cyclical heat engine can do only \(\displaystyle 1.50×10^5J\) of work. (b) 24%. Heat transfer \(\displaystyle Q\) and work done \(\displaystyle W\) are always energy in transit, whereas internal energy \(\displaystyle U\) is energy stored in a system. (d) \(\displaystyle 8.29×10^{12}J\). (b) \(\displaystyle Eff_2=1−\frac{423K}{543K}=0.221\) or \(\displaystyle 22.1%\) (a) How much food energy will a man metabolize in the process of doing 35.0 kJ of work with an efficiency of 5.00%? Practice: Thermodynamics questions. 6. A great deal of effort, time, and money has been spent in the quest for the so-called perpetual-motion machine, which is defined as a hypothetical machine that operates or produces useful work indefinitely and/or a hypothetical machine that produces more work or energy than it consumes. What is a possible explanation? Legal. These are practice examination questions on thermodynamics for A-Level Physics. (c) Work done by the motor is \(\displaystyle 1.61×10^7\); thus the motor produces 7.67 times the work done by the man. 31. The energy content of gasoline is \(\displaystyle 1.3×10^8J/gal\). Suppose both have the same heat transfer into the engine in one day, \(\displaystyle 2.50×10^{14}J\). (Essentially: conservation of energy). Solution We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. (b) How much heat transfer occurs to the environment to keep his temperature constant? Compare this efficiency to the thermodynamic efficiency quoted for gasoline engines and discuss why the thermodynamic efficiency is so much greater. (b) \(\displaystyle 1.60×10^{14}J\) Describe the photo of the tea kettle at the beginning of this section in terms of heat transfer, work done, and internal energy. Imagine you are driving a car up Pike’s Peak in Colorado. (a) How much more electrical energy is produced by the more efficient power station? Is it consistent with the fact that you quickly warm up when exercising? 11. (b) \(\displaystyle 3.28×10^{31}J\). 48. to estimate required balances of heat, work and energy flow. 69. What is the coefficient of performance of an ideal heat pump that has heat transfer from a cold temperature of \(\displaystyle −25.0ºC\) to a hot temperature of \(\displaystyle 40.0ºC\)? But other considerations have to be taken into account. (c) If the cost of this work input is \(\displaystyle 10.0 cents/kW⋅h\), how does its cost compare with the direct heat transfer achieved by burning natural gas at a cost of 85.0 cents per therm. 35. How much a) work is done and b) heat is transferred in this process? What does this do to the entropy of the universe? (Assume the temperature of the environment is \(\displaystyle 20ºC\).). A real process may be nearly adiabatic if it occurs over a very short time. (a) \(\displaystyle 244ºC\) In this question, the coffee is in equilibrium with both the milk and the sugar, allowing us to conclude that the milk and sugar must be in equilibrium with … (a) A woman climbing the Washington Monument metabolizes \(\displaystyle 6.00×10^2kJ\) of food energy. (a) \(\displaystyle 18.5kJ\) A-Level Chemistry. 89. (c) What increase in entropy is produced by mixing 20.0 kg of \(\displaystyle 90.0º C\) water with 20.0 kg of \(\displaystyle 10.0º C\) water? 34. 32. How much heat transfer occurs from the rock? In a very mild winter climate, a heat pump has heat transfer from an environment at \(\displaystyle 5.00ºC\) to one at \(\displaystyle 35.0ºC\). Is a temperature difference necessary to operate a heat engine? Explicitly show how you follow the steps in the Problem-Solving Strategy for thermodynamics found in Problem-Solving Strategies for Thermodynamics. (c) If you were betting on 2 heads and 8 tails would you accept odds of 252 to 45? 94. Grocery store managers contend that there is less total energy consumption in the summer if the store is kept at a low temperature. AQA A Level Physics revision resources. (b) \(\displaystyle 1.66×10^8J\) or \(\displaystyle 3.97×10^4kcal\) Here are a few important concepts that need to be covered while preparing for this chapter: The first law of thermodynamics. 18. 1) QUES: A piece of brass undergoes 3 different processes involving change of energy: P : it is lifted vertically 2m Q : it is heated from 15 degrees Celsius to 20 degrees Celsius R : it is accelerated from … We ordinarily say that \(\displaystyle ΔU=0\) for an isothermal process. 52. Solution Assume that prior to the upgrade the power station had an efficiency of 36% and that the heat transfer into the engine in one day is still the same at \(\displaystyle 2.50×10^{14}J\). A rapidly spinning paddle wheel raises the temperature of 200mL of water from 21 degrees Celsius to 25 degrees. 90. (c) To transfer \(\displaystyle 1.66×10^8J\), heat pump costs $1.00, natural gas costs $1.34. (a) Construct a table showing the macrostates and all of the individual microstates for tossing 6 coins. \(\displaystyle Eff_{overall}=1−(1−0.249)(1−0.221)=41.5%\) If her efficiency is 18.0%, how much heat transfer occurs to the environment to keep her temperature constant? (a) How much heat transfer occurs to the environment? A hand-driven tire pump has a piston with a 2.50-cm diameter and a maximum stroke of 30.0 cm. How much heat transfer occurs to the environment? Subscribe to A Level Physics to access 400+ resources, plus 15 new Factsheets each year. is the enthalpy … (a) If you toss 10 coins, what percent of the time will you get the three most likely macrostates (6 heads and 4 tails, 5 heads and 5 tails, 4 heads and 6 tails)? (a) What is the hot reservoir temperature of a Carnot engine that has an efficiency of 42.0% and a cold reservoir temperature of \(\displaystyle 27.0ºC\)? (c) What is the overall efficiency of the two engines? The University does not release solutions to past exam questions, but numerical answers are: 2013 (b) Qout=500kJ, max … Since the body is inefficient, the excess heat produced must be dissipated through sweating, breathing, etc. (b) What is unreasonable about the engine? Specific heat and latent heat of fusion and vaporization. (e) Discuss how everyday processes make increasingly more energy unavailable to do work, as implied by this problem. A large electrical power station generates 1000 MW of electricity with an efficiency of 35.0%. (c) Compare his work output with the daily output of a 187-W (0.250-horsepower) motor. Would the previous question make any sense for an isochoric process? Yes, the answer is the same. Explain your answer. Solution (b) 5.6 times more likely (a) \(\displaystyle 1.32 × 10^9J\) Among the things to consider are the effective hot and cold reservoir temperatures. 4. If so, does the entropy increase or decrease? 21. Calculate whether we can bring the relative humidity in the office up to the comfortable level by closing the air vents and putting a cup of … (b) How much less heat transfer occurs to the environment due to the upgrade? 57. (b) Since \(\displaystyle 270ºC\) steam is still quite hot, a second steam engine is sometimes operated using the exhaust of the first. This states: If two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other. 80. Consider a car’s gasoline engine. (homework, quiz, self-assessment, PRS) 5) To be able to explain at a level understandable by a high school senior or non-technical person the … (e) 3.33 times more likely (20 to 6). What is wrong with the claim that a cyclical heat engine does 4.00 kJ of work on an input of 24.0 kJ of heat transfer while 16.0 kJ of heat transfers to the environment? Explain your answer. What is the hot reservoir temperature for such a refrigerator? Give Its Limitations And Importance.? What is the change in internal energy of a system which does \(\displaystyle 4.50×10^5J\) of work while \(\displaystyle 3.00×10^6J\) of heat transfer occurs into the system, and \(\displaystyle 8.00×10^6J\) of heat transfer occurs to the environment? (a) On a winter day, a certain house loses \(\displaystyle 5.00×10^8J\) of heat to the outside (about 500,000 Btu). (a) A cyclical heat engine, operating between temperatures of \(\displaystyle 450º C\) and \(\displaystyle 150º C\) produces 4.00 MJ of work on a heat transfer of 5.00 MJ into the engine. 76. So, no, you wouldn’t bet on odds of 252 to 45. 22. The actual efficiency is 96% of the Carnot efficiency, which is much higher than the best-ever achieved of about 70%, so her scheme is likely to be fraudulent. The temperature of a rapidly expanding gas decreases. 100. (b) Find the ratio of this efficiency to the Carnot efficiency of a standard nuclear reactor (found in Example). 65. Solution As you know, we use a lot of energy to keep our houses warm in the winter because of the loss of heat to the outside. 98. Have questions or comments? Give an example of a spontaneous process in which a system becomes less ordered and energy becomes less available to do work. What temperature of hot steam must you use? (a) If tossing 100 coins, how many ways (microstates) are there to get the three most likely macrostates of 49 heads and 51 tails, 50 heads and 50 tails, and 51 heads and 49 tails? The temperature of a body is increased from -173 C to 357 C. First law of thermodynamics. (Hint: Consider whether the gas does work and whether heat transfer occurs rapidly into the gas through conduction.). 79. 2. A system does \(\displaystyle 1.80×10^8J\) of work while \(\displaystyle 7.50×10^8J\) of heat transfer occurs to the environment. In this article, students will get notes of chapter Thermodynamics including topics important concepts, formulae and previous years’ solved questions for WBJEE 2018. These are the answers to the further solids practice questions for A-Level Physics. Consider a system with a certain energy content, from which we wish to extract as much work as possible. refers to the second law of thermodynamics. 62. 88. (b) Now find the amount of work by calculating the force exerted times the distance traveled. (a) What is the change in entropy if you start with 100 coins in the 45 heads and 55 tails macrostate, toss them, and get 51 heads and 49 tails? (a) By calculating \(\displaystyle PΔV\), find the work done by the steam when the piston moves 0.800 m. Note that this is the net work output, since gauge pressure is used. Created by teachers for Physics revision. (d) Calculate the amount of work made unavailable by this mixing using a low temperature of \(\displaystyle 10.0º C\), and compare it with the work done by the Carnot engine. 23. To understand this concept we must first appreciate what thermal equilibrium is. How much heat transfer occurs from a system, if its internal energy decreased by 150 J while it was doing 30.0 J of work? Set 1 - This test comprises of 50 questions on Thermodynamics. (Consult Table.). The heat and thermodynamics chapter is very important as every year 2 to 3 questions can always be expected from this chapter. A coal-fired electrical power station has an efficiency of 38%. Physics problems: thermodynamics. Give an explanation of how food energy (calories) can be viewed as molecular potential energy (consistent with the atomic and molecular definition of internal energy). Explicitly show how you follow the steps in the Problem-Solving Strategies for Entropy. These are practice examination questions on thermodynamics for A-Level Physics. The second law of thermodynamics. (One type of more efficient nuclear power station, the gas-cooled reactor, has not been reliable enough to be economically feasible in spite of its greater efficiency.). … 82. Thermodynamics Multiple choice Questions and answers pdf,mcqs,objective type questions,lab viva manual technical basic interview questions download. (a) 492 kJ (c) How much work is made unavailable, taking the lowest temperature to be \(\displaystyle 20.0º C\)? A certain heat engine does 10.0 kJ of work and 8.50 kJ of heat transfer occurs to the environment in a cyclical process. 14. (b) \(\displaystyle 2.10×10^6J\) In which of the paths between initial state i and final state f in the below figure is … (a) What is the decrease in her internal energy, assuming no change in temperature or consumption of food? These are the answers to the work energy and power practice questions for A-Level Physics. 4 Temperature and Thermal Properties (Questions) * ..... 125 Temperature and Thermal Properties (Answers) ..... 126 47. (b) Discuss the amount of heat transfer found in (a). (b) 0.667 barrels. (a) What is the best coefficient of performance for a refrigerator that cools an environment at \(\displaystyle −30.0ºC\) and has heat transfer to another environment at \(\displaystyle 45.0ºC\)? Can they eliminate heat transfer into the environment entirely? (a) What is the average metabolic rate in watts of a man who metabolizes 10,500 kJ of food energy in one day? When \(\displaystyle 1.60×10^5J\) of heat transfer occurs into a meat pie initially at \(\displaystyle 20.0º C\), its entropy increases by 480 J/K. energy.Write just one answer, it is the same for both question marks. 12. (b) \(\displaystyle 477ºC\) What is the best coefficient of performance possible for a hypothetical refrigerator that could make liquid nitrogen at \(\displaystyle −200ºC\) and has heat transfer to the environment at \(\displaystyle 35.0ºC\)? Explain your answer. Explicitly show how you follow the steps in the Problem-Solving Strategies for Thermodynamics. (b) What average force do you exert on the piston, neglecting friction and gravitational force? 46. Solution (b) How much heat transfer occurs into the warm environment if \(\displaystyle 3.60×10^7J\) of work (10.0kW⋅h) is put into it? Zeroth law of thermodynamics. 5. Created by teachers for Physics revision. (b) How much heat transfer occurs to the environment? The total number of microstates in that range is \(\displaystyle 1.22×10^{30}\). Solution The First Law of Thermodynamics Work and heat are two ways of transfering energy between a system and the environment, causing the system’s energy to change. Why—other than the fact that the second law of thermodynamics says reversible engines are the most efficient—should heat engines employing reversible processes be more efficient than those employing irreversible processes? State The Third Law Of Thermodynamics. To raise a car weighing 1000 kilograms a distance of 100 meters would require about a million joules. A car tire contains \(\displaystyle 0.0380m^3\) of air at a pressure of \(\displaystyle 2.20×10^5N/m^2\) (about 32 psi). Is the answer the same as in part (a)? Is that process also the one with the smallest work input required to return it to point A? (b) What is unreasonable about the temperature? (b) 40 cents The zeroth law of thermodynamics states that if an object X is in thermal equilibrium with object Y, and object Y also in thermal equilibrium with object Z, then object X must also be in thermal equilibrium with object Z. refers to the first law of thermodynamics. Describe in detail how you evaluate the relative costs. Even though thermodynamics may appear to be somewhat uninteresting to some of you, you should note that at the AP Physics B level you will often get unusually simple questions. Does its entropy change? The Carnot efficiency is \(\displaystyle Eff_C=1−\frac{T_c}{T_h}=1−\frac{300K}{600K}=0.50\). No part of our online resources may be reproduced or reused for any commercial purpose, or transmitted, in any other form or by any other means, without the prior permission of Curriculum Press Ltd. I take the latter view. (d) \(\displaystyle Eff_{overall}=1−\frac{423K}{723K}=0.415\) or \(\displaystyle 41.5%\), 70. (b) The temperature is too cold for the output of a steam engine (the local environment). (b) This amount of heat is consistent with the fact that you warm quickly when exercising. Using Table, verify the contention that if you toss 100 coins each second, you can expect to get 100 heads or 100 tails once in \(\displaystyle 2×10^{22}\) calculate the time to two-digit accuracy. What is the decrease in entropy of 25.0 g of water that condenses on a bathroom mirror at a temperature of \(\displaystyle 35.0º C\), assuming no change in temperature and given the latent heat of vaporization to be 2450 kJ/kg? I have some questions on Thermodynamics on A-level physics. The effective temperature of deep space is \(\displaystyle −270º C\). First law of thermodynamics problem solving. (c) \(\displaystyle 2.85×10^{10}J/K\) The Sun radiates energy at the rate of \(\displaystyle 3.80×10^{26}W\) from its \(\displaystyle 5500º C\) surface into dark empty space (a negligible fraction radiates onto Earth and the other planets). Note that the energy efficiency rating (\(\displaystyle EER\)) of an air conditioner or refrigerator is defined to be the number of British thermal units of heat transfer from a cold environment per hour divided by the watts of power input. 83. She is standing at 28.5 m from the earth surface level. (c) The assumed efficiency is too high. 58. Solution (b) \(\displaystyle 54.1%\). Can improved engineering and materials be employed in heat engines to reduce heat transfer into the environment? Solution (d) What percent chance is there of tossing 5 heads and 1 tail? 25. 1. Explain your answer. chemical engineering? 85. Explain why. (b) How much work does it produce for 100 kJ of heat transfer into the engine? 59. What is its coefficient of performance? (b) What would the maximum efficiency of this steam engine be if its cold reservoir temperature were \(\displaystyle 150ºC\)? 42. Appendix 6: Mathematical skills and exemplifications). Hi. 64. 87. On a hot summer day, \(\displaystyle 4.00×10^6J\) of heat transfer into a parked car takes place, increasing its temperature from \(\displaystyle 35.0º C\) to \(\displaystyle 45.0º C\). This work is licensed by OpenStax University Physics under a Creative Commons Attribution License (by 4.0). 10. 30. ... at sea level (b) at the center of the earth (c) when molecular momentum of the system becomes zero (d) under vacuum conditions \(\displaystyle ∴(1−Eff_{overall})=(1−Eff_1)(1−Eff_2)\) 37. 5.1 Thermodynamics notes. (a) \(\displaystyle 3.80 × 10^9J\) Is this orderly or disorderly? Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. (c) Discuss whether this cost seems realistic. Start with the definitions of the \(\displaystyle COP\) s and the conservation of energy relationship between \(\displaystyle Q_h, Q_c,\) and \(\displaystyle W\). (a) \(\displaystyle 1.04×10^{31}J/K\) (b) What must the hot reservoir temperature be for a real heat engine that achieves 0.700 of the maximum efficiency, but still has an efficiency of 42.0% (and a cold reservoir at \(\displaystyle 27.0ºC\)? All other factors, such as the car’s temperature, are constant. If heat flows from a cup of hot water to a bathtub full of cool water, the water in the cup will have a loss in ? Questions organised by topic, past papers & mark schemes. (a) How long will the energy in a 1470-kJ (350-kcal) cup of yogurt last in a woman doing work at the rate of 150 W with an efficiency of 20.0% (such as in leisurely climbing stairs)? Explain your responses. (b) How much heat transfer to the environment takes place? Among the factors to be considered are the gain in altitude and speed, the mass of the car, the distance traveled, and typical fuel economy. (b) \(\displaystyle –8.30 × 10^{12}J\), where the negative sign indicates a reduction in heat transfer to the environment. Explain why a building made of bricks has smaller entropy than the same bricks in a disorganized pile. (c) What is the total number of microstates? The heat transfer to the cold reservoir is \(\displaystyle Q_c=Q_h−W=25kJ−12kJ=13kJ\), so the efficiency is \(\displaystyle Eff=1−\frac{Q_c}{Q_h}=1−\frac{13kJ}{25kJ}=0.48\). 36. Find the increase in entropy of 1.00 kg of liquid nitrogen that starts at its boiling temperature, boils, and warms to \(\displaystyle 20.0º C\) at constant pressure. These are the answers to the liquids & gases practice questions for A-Level Physics. Driving up Pike's Peak (a mere 3000-meter climb) should consume a little less than a quart of gas. Does the entropy of the space into which it radiates (which has a temperature of about 3 K) increase or decrease? 28. How does the definition of efficiency in each relate to the type of energy being converted into doing work? (Take the ratio of the number of microstates to find out. (Use Table as a guide.). If you run down some stairs and stop, what happens to your kinetic energy and your initial gravitational potential energy? How does the short time span help the process to be adiabatic? Explain why in terms of the first law of thermodynamics. Explicitly show how you follow the steps in the Problem-Solving Strategies for Thermodynamics. (Take the ratio of the number of microstates to find out.). (a) \(\displaystyle 8.30 × 10^{12}J\), which is 3.32% of \(\displaystyle 2.50 × 10^{14}J\). 43. (b) What is the change in entropy due to this heat transfer? (b) This large change in entropy implies a large amount of energy has become unavailable to do work. Questions on heat and thermodynamics for Principles of Engineering. Can you cool a kitchen by leaving the refrigerator door open? In the German world it is often seen as an a diﬀerent ﬁeld from statistical mechanics. ), Solution Explain what she is likely to find, in terms of the second law of thermodynamics. tistical mechanics. (b) In order to gain more energy, we must generate it from things within the house, like a heat pump, human bodies, and other appliances. Compare your calculated efficiency with the actual efficiency of car engines. The paper will include questions that target mathematics at Level 2 or above (see . (b) What is the ratio of heat transfer to the environment to work output? (That is, there is no other energy transfer. The temperature of the steam leaving the boiler is \(\displaystyle 550ºC \). 14: Heat and Heat Transfer Methods (Exercises), 16: Oscillatory Motion and Waves (Exercises), 15.2: The First Law of Thermodynamics and Some Simple Processes, 15.3 Introduction to the Second Law of Thermodynamics: Heat Engines and Their Efficiency, 15.4 Carnot’s Perfect Heat Engine: The Second Law of Thermodynamics Restated, 15.5: Applications of Thermodynamics: Heat Pumps and Refrigerators, 15.6: Entropy and the Second Law of Thermodynamics: Disorder and the Unavailability of Energy, 15.7: Statistical Interpretation of Entropy and the Second Law of Thermodynamics: The Underlying Explanation, Creative Commons Attribution License (by 4.0). Identify the type of energy transferred to your body in each of the following as either internal energy, heat transfer, or doing work: (c) riding an elevator to a higher floor. Solution One method of converting heat transfer into doing work is for heat transfer into a gas to take place, which expands, doing work on a piston, as shown in the figure below. 33. A gas-cooled nuclear reactor operates between hot and cold reservoir temperatures of \(\displaystyle 700ºC\) and \(\displaystyle 27.0ºC\). 24. 91. (d) 9.38% Welcome to 5.1 THERMODYNAMICS. A Level physics question Something for nothing? (a) What is the maximum efficiency of a heat engine operating between these temperatures? Part 1 Problem 1. What is the increase in entropy of the car due to this heat transfer alone? (a) What is the work output of a cyclical heat engine having a 22.0% efficiency and \(\displaystyle 6.00×10^9J\) of heat transfer into the engine? How much more internal energy does this gas have than the same volume has at zero gauge pressure (which is equivalent to normal atmospheric pressure)? (a) Is the heat transfer converted directly to work in an isobaric process, or does it go through another form first? It should happen twice in every \(\displaystyle 1.27×10^{30}s\) or once in every \(\displaystyle 6.35×10^{29}s\) Solution (a) In reaching equilibrium, how much heat transfer occurs from 1.00 kg of water at \(\displaystyle 40.0º C\) when it is placed in contact with 1.00 kg of \(\displaystyle 20.0º C\) water in reaching equilibrium? Email [email protected] Phone 01952 271 318. A woman shuts her summer cottage up in September and returns in June. (a) What is the change in entropy if you start with 10 coins in the 5 heads and 5 tails macrostate, toss them, and get 2 heads and 8 tails? Missed the LibreFest? (a) 4.61 Resources About Services Blog Contact Resources About Services Blog Suppose you want to operate an ideal refrigerator with a cold temperature of \(\displaystyle −10.0ºC\), and you would like it to have a coefficient of performance of 7.00. The materials published on this website are protected by the Copyright Act of 1988. Work while \ ( \displaystyle ΔU=0\ ) for an isothermal process cents per \ ( 7.50×10^8J\... Certain gasoline engine has an efficiency of 35.0 % why the thermodynamic efficiency is 18.0 %, how heat... To estimate required balances of heat transfer found in Problem-Solving Strategies for entropy specifically explain! Hint: consider whether the gas does work and isobaric … these are the effective hot cold. Ideal heat pump is being converted into doing work little less than a quart gas... ), in terms of efficiency for the human body and heat to. Entropy than the same as in part ( a ) \ ( W=PΔV=1.76×10^5J\... This section ( Figure ). ). ). ). ). ) )! Quart of gas hot steam temperature of 200mL of water from 21 degrees Celsius 25. 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Or consumption of food energy this cost seems realistic by OpenStax University Physics under a Creative Commons Attribution License by. Process be precisely adiabatic for a heat engine operating between these temperatures of 17.0 % operate! Part 1: work and 8.50 kJ of food as much work does it produce 100. Specifically, explain What happens to the efficiency of car engines metabolic rate watts... Formed ( the number of microstates in each macrostate ). ). ) )! German world it is still warm in these houses than for path ABCDA improved engineering and materials be in! The residents are not at home, it is still warm in these houses taking lowest... Power practice questions for A-Level Physics ’ t bet on odds of 252 45. Section ( Figure ). ). ). ). ). ). ). ) ). And latent heat of the total number of microstates to find out. ). )... 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And energy flow 25 degrees by OpenStax University Physics under a Creative Commons Attribution License ( by )... Temperature if the pump is to have a coefficient of performance for these temperatures freezers in the store is at! Mere 3000-meter climb ) should consume a little less than for path?. Each type of energy being converted 30.0 cm info @ libretexts.org or check our! You cool a kitchen by leaving the boiler is \ ( \displaystyle Q_h\ ), solution ( a ) the. Consume a little less than for path ABCDA in the types of energy considered of gas heat and heat. Temperatures of \ ( \displaystyle Eff_C=1−\frac { T_c } { T_h } =1−\frac { }. Is this thermal ef- Edexcel a level Physics revision resources =1−\frac { 300K } T_h! To consider are the answers to the efficiency of 35.0 % more electrical energy is due! A macroscopic system imagine you are driving a car weighing 1000 kilograms a distance of meters! For tossing 6 coins May 2013 and May 2014 papers for engineering thermodynamics water the! Tire pump has a piston with a hot steam temperature of \ ( \displaystyle COP\.... Engine can have of energy being converted and returns in June \displaystyle \! And stop, What factors May keep you from realizing your ideal use. Count the number of ways that each could be formed ( the of! Reservoir temperatures required to return it to point a: consider whether the gas does work and 9500 of! T_H } =1−\frac { 300K } { 600K } =0.50\ ). ). ). )..! Important concepts that NEED to be taken into account that there is no other energy transfer high temperature contact... A woman shuts her summer cottage up in September and returns in June freezers in the English speaking of! E ) Discuss how everyday processes make increasingly more energy unavailable to do work mechanisms are one of! Gasoline into its tank without heat transfer to the environment due to this heat transfer the. Discuss whether this cost seems realistic freezers in the types of energy considered practical steam utilize. Of \ ( \displaystyle COP\ ). ). ). ). ). ) )... Work by calculating the force exerted times the distance traveled 3 tails than 5 heads and 8 tails heat occurs! Of any type the same bricks in a cyclical process, UPSC and other exams. Isothermal unless it is either in transit or resides in a disorganized.... Is unlikely that a process can be isothermal unless it is either in transit or in... Seen as a subset of the maximum efficiency this engine one has the! Vary depending on how energy is being considered for use in heating an environment a! Basic definitions how hard is chemical engineering without Physics a level Physics resources., \ ( \displaystyle 20ºC\ ). ). ). ). ). ) )! Body and heat engines to reduce heat transfer from another system help the process twice a minute steam, is! The average metabolic rate in watts of a standard nuclear reactor operates between hot and cold reservoir temperatures how... Can heat transfer occurred prior to the further solids practice questions for Physics. Estimate required balances of heat transfer occurs to the further solids practice questions for A-Level Physics built without systems. \Displaystyle 550ºC \ ) ( b ) 5.00 % in these houses 1.22×10^ 30! The number of ways that each could be formed ( the number of microstates in each )., \ ( \displaystyle 1.22×10^ { 30 } \ ). ). ) )! Has smaller entropy than the same heat transfer occurred prior to the entropy increase or decrease day \! Latent heat of the maximum efficiency of the car ’ s temperature, are constant May! Arguments to support or refute this claim, taking into account of 252 45... We find more energy when such energy is produced by the more efficient power station has. 10.0 kJ of heat transfer occurs to the entropy of the a level physics thermodynamics questions law of thermodynamics number of heads and about... Whether the gas through conduction. ). ). ). ) )! Engine be if its exhaust has a piston with a temperature of \ ( \displaystyle ×! J of work and 8.50 kJ of heat is consistent with the fact that you warm! Tails than 2 heads and 25 tails a third system, they are also in equilibrium! Vary depending on how energy is being converted into doing work can you cool a kitchen leaving! Does \ ( \displaystyle 1.80×10^8J\ ) of work while \ ( \displaystyle 18.5kJ\ ) ( b ) much... True for isobaric and isochoric processes 4.0 ). ). ). )..... Of 252 to 45 and latent heat of fusion and vaporization in internal energy of a heat engine can....

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